The present disclosure relates to methods and systems for removing liquid hydrocarbon compounds, such as but not limited to oil, fuels, lubricants, liquid hydrocarbons, or crude oil (collectively referred to herein as “oil”), for example, from bodies of water. A body of water may be fresh water or salt water, such as an ocean, bay, harbor, river, inland lake, or the like, and has a surface portion or area. The body of water exists adjacent a land area, and they meet and adjoin one another at a bank, beach, or the like. The present disclosure also relates to methods and systems for recovering (i.e., reclaiming) the removed oil.
The need for removal of oil leakages, slicks, and spills (collectively referred to herein as “spills”) from bodies of water and, to a lesser degree, for recovery of the removed oil, is well known. Oils spills are often due to releases from tankers, barges, or from offshore drilling operations, and may occur in rivers in addition to oceans, seas, gulfs, and lakes. Oil may be present on and under the surface of a body of water and on any land that the water touches, and damages and kills aquatic and terrestrial life, affects food sources obtained from those waters, and ruins neighboring beaches. Areas affected by oil spills are economically affected due to the inability to practice livelihoods dependent upon the waters and beaches such as fishing, shrimping, and tourism.
Although cleaning up oil spills from the surface of the water and below the surface of the water is a challenging and costly procedure, the problem of cleaning up oil spills from the surface of the water is a concern not only from an economic aspect but also because of the resulting marine biological impact of such spills. It is also known that layers of oil upon bodies of water resulting from the accidental or purposeful discharge of oils into a body of water produce a surface film that may be combustible and endangers the area.
Furthermore, one of the problems encountered subsequent to removal of oil from the surface of water, is the physical disposal of the large volumes of oil involved. Preferably, it is recovered for a useful purpose rather than to be disposed of in a landfill.
A typical proposed solution in dealing with the problem of a spill on a body of water is providing means to partially or completely surround the area of oil accumulation on the water with floating barriers or booms and then to pump the accumulated oil to a desirable storage area or burn it off. Recovery of or burning off the oil are challenging due to the fact that oil spills usually cover a large area and the water may be moving.
Another typically proposed solution is to place oil absorbing materials on or below the surface of the water in contact with the spill to collect the oil.
Once oil at or below the surface of water is removed, there remains the problem of how to dispose of the oil and/or the media used to remove the oil from the water. Typically, these oil-coated materials are waste products.
Another challenge to removal and/or recovery of the oil has been that many of the traditionally used materials such as, for example, straw, vermiculite, or sawdust, also absorb a large amount of water, which decreases the amount of oil that those materials can absorb. The development of hydrophobic and oleophilic media has been helpful in this regard, and such materials are now commonly in use for selective removal of oil from water. One such material is oleophilic polypropylene. Such media is known by those having ordinary skill in the relevant art as a white sorbent, and is commonly produced in pad form, typically rectangular 12×16 inches in area and approximately ¼ inch thick, and often referred to as white board or white pad. Although this oil removal media has obvious advantages, a big drawback relates to the recovery of removed oil and/or the ultimate disposition of the media. When coated with oil this media is essentially a waste product, and although some amount of oil collected thereon may be recovered by scraping the oil off its surfaces, most of the oil remains absorbed therein and cannot be mechanically extracted therefrom. Regardless of whether some amount of collected oil is recovered from it, the used white sorbent media is disposed of rather than reused.
Selective removal of oil spills floating on surfaces of bodies of water may also entail use of hydrophobic and oleophilic open-celled foams having capacity for removing oil primarily by absorption. Such a foam is disclosed in U.S. Pat. No. 3,819,514, the entire disclosure of which is hereby incorporated herein by reference. These oil absorbent materials may also be oil adsorbent, and the oil stays in the media due to polarity. An absorbent allows a substance to enter it, i.e., it takes in another substance; whereas with an adsorbent, the substance is adhered to the surface of the adsorbent. Recovery of the removed oil may be done by squeezing these foams, and the foam may be reused a limited number of times for oil removal and recovery before ultimately being disposed of. Preferably, the foam is biodegradable so that it will degrade when eventually placed in a landfill. Selective removal of oil spills floating on surfaces of bodies of water may also be accomplished through use of improved open-cell foam media in the form of pads that absorb the oil, such as OPFLEX™ media commercially available from Opflex Technologies, LLC and described in Patent Publication No. US 2011/0287929 A1, the entire disclosure of which is hereby incorporated herein by reference. OPFLEX™ media adsorbs and absorbs oil, repels water, and is reusable five to more than ten times, which also reduces transportation costs relative to white sorbent media, which is not reusable. Despite its relatively higher initial cost, the ability to reuse OPFLEX™ can result in material cost parity with white board. Notably, 90 percent of the oil collected by OPFLEX™ media can be recovered through a wringer or centrifuge process. Moreover, OPFLEX™ media absorbs twice as much oil per square foot as comparably thick white board, and is biodegradable whereas the white sorbents are not. Studies have been performed which demonstrate that the use of OPFLEX™ results in 90 percent less oil-collecting media and 90 percent less oil being sent to a landfill, compared to white sorbents. Further, the substantially increased ability to recover oil from a spill using OPFLEX™ media, vis-à-vis white board, is expected to more than offset any relatively higher costs associated with labor and/or material.
In a preliminary comparative test relating to North Dakota Bakken Crude, ¼ gallon (i.e., approximately 946 ml) of the oil was poured into each of two separate tanks of water, and respectively collected by identically sized pads of OPFLEX™ media and white board. The collected oil was recovered by using a wringer from both media types. One and a half OPFLEX™ pads recovered 650 ml of the oil, whereas three white board pads recovered 110 ml. The one and a half OPFLEX™ pads were redeployed in a tank containing an additional ¼ gallon of Bakken Crude to recover an additional 175 ml of the oil, for a total recovery of 825 ml after one redeployment.
Further preliminary Bakken Crude tests and economic analysis yielded the net cost comparison associated with a 100,000 gallon spill cleanup shown in TABLE 1:
TABLE 1Economic Analysis/Comparison:Net Cost to Clean up 100,000-Gallons Oil SpillBakken CrudeProductCategoryWhite BoardOPFLEXAvg Adsorption (gal/100 sq-ft)6.27    12.501st UseAvg Adsorption (gal/100 sq-ft)0.00    12.502nd-5th UsePerformance Removal (pads/gallon)12    6Number of Uses per Pad1 (once)5 cycles throughwringerTotal Pads Required1.2 million 120,000Price per Pad (15 × 17)$.30    $3.00Total Cost for Pads$360,000$360,000Recovery of Oil - GallonsNone/Limited 90,000Recovery of Oil - BarrelsNone/Limited  2,150Credit Oil Recovered ($100 per bbl)0($215,000)Net Cost (Pads Cost plus Credit)$300,000$145,000Note:Additional research required
In a similar preliminary test relating to Alberta Oil Sands, ½ gallon of the oil was poured into each of two separate tanks of water, and respectively collected by identically sized pads of OPFLEX™ media and white board, with the collected oil recovered from both media types by using a wringer. On their initial deployment, 3¼ OPFLEX™ pads recovered 775 ml of oil, whereas five white pads recovered 350 ml. Three used OPFLEX™ pads were redeployed in a tank containing an additional ¼ gallon of Alberta Oil Sands to recover an additional 50 ml of the oil, for a total recovery of 825 ml after one redeployment.
Further preliminary Oil Sands tests and economic analysis yielded the net cost comparison associated with a 100,000 gallon spill cleanup shown in TABLE 2:
TABLE 2Economic Analysis/Comparison:Net Cost to Clean up 100,000-Gallons Oil SpillCanadian Oil SandsProductCategoryWhite BoardOPFLEXAvg Adsorption (gal/100 sq-ft)7.50    11.601st UseAvg Adsorption (gal/100 sq-ft)0.00     5.802nd-8th UsePerformance Removal (pads/gallon)10    6.5Number of Uses per Pad1 (once)8 cycles throughwringerTotal Pads Required1.0 million 130,000Price per Pad (15 × 17)$.30    $3.00Total Cost for Pads$300,000$390,000Recovery of Oil - GallonsNone/Limited 90,000Recovery of Oil - BarrelsNone/Limited  2,150Credit Oil recovered ($100 per bbl)0($215,000)Net Cost (Pads Cost plus Credit)$300,000$175,000Note:Additional research required
From the above test results, OPFLEX™ media clearly provides advantages over white sorbent media. At present, however, pads of either media type are typically deployed in a manner that entails manually, and rather slowly, placing or removing the rather small pads. Given that a 2000 oil gallon spill on a body of water can cover a surface area approximately equal to that of six football fields (i.e., about 360,000 square feet), removing such a spill in the above-described manner, regardless of media type used, can be very labor intensive and slow.
In view of the large sizes of many spills, a system and method for quickly deploying the media over a widespread area, and for optionally recovering the oil collected by the media, would represent a significant advancement in the relevant art.